Vasopressin is increased in mineralocorticoid-induced blood pressure increase in man.

Vasopressin has been studied intensively in DOCA-salt rats and seems to play an important role in this model of hypertension. In the present study we investigated plasma vasopressin in seven normotensive young volunteers during the early phase of mineralocorticoid-induced hypertension. We administered 0.8 mg/day fludrocortisone for 1 week. Body weight, blood pressure, plasma vasopressin, plasma osmolality and electrolytes, as well as plasma renin activity, were evaluated on days 0, 3 and 7. Blood pressure increased significantly from 117/67 to 121/76 mmHg (P less than 0.05) within 1 week, while plasma osmolality remained unaltered at 284 +/- 3 mOsmol/l. Plasma vasopressin (0.45 +/- 0.1 pg/ml) was increased after 3 days (0.68 +/- 0.5 pg/ml) and rose further to 1.53 +/- 0.27 pg/ml after 1 week (P less than 0.05). Changes in plasma vasopressin concentration were not correlated with alterations in blood pressure. Our results show an increase in plasma vasopressin in the early phase of mineralocorticoid-induced hypertension in man. However, the observed increase is moderate and does not seem to explain the increase in blood pressure alone, but could contribute to the blood pressure increase during mineralocorticoid treatment.